A liquid crystal display device typically includes a lower substrate including a light blocking layer, a color filter, and an ITO pixel electrode; an active circuit portion including a liquid crystal layer, a thin film transistor, and a capacitor layer; and an upper substrate including an ITO pixel electrode.
The light blocking layer blocks uncontrolled light transmitted out of a transparent pixel electrode of a substrate to prevent contrast reduction by the light transmitted through a thin film transistor. Red, green and blue light blocking layers transmit light with a predetermined wavelength of white light and display colors.
The light blocking layer is generally fabricated using a pigment dispersion method. The pigment dispersion method includes coating a transparent substrate with a colorant-containing photopolymerizable composition, exposing the coating to provide a pattern by thermal curing, and removing non-exposed portions with a solvent.
When a photosensitive polyimide or phenol-based resin is used as a binder resin in the pigment dispersion method, high heat resistance may be obtained but sensitivity can be reduced and an organic solvent is required as a development solvent. A photoresist using an azide compound can have low sensitivity and heat resistance and may be affected by oxygen during exposure.
An acrylic-based resin can also be used as a binder resin in the pigment dispersion method. An acrylic-based resin can have good heat resistance, shrinkage-resistance, chemical resistance, and the like, but also can have reduced sensitivity, developability, and close contacting (adhesion) properties. Since black pigments are included in a large amount in order to adjust optical density of a light blocking layer, sensitivity, development properties, and close contacting properties may also be significantly deteriorate.